How tension will change with an increase in electrical charge

1. How does the magnitude of the electric field strength () depend on the distance to the center of a uniformly charged hollow sphere (is the radius of the sphere)? When< () = , при > () = .

2. An equipotential surface is a surface, at each point of which ... the potential has the same

value, the vector of the electric field strength is normal to the surface.

Which figure correctly represents the potential graph for case 1< 0,2 > 0? 3.

The charged soap bubble inflates. How will its electrical capacity change and electric Energy? Capacity

increases, energy decreases.

Density of electric current in a medium with specific conductivity and resistivity at tension

the electrostatic field and the field strength of the side forces is

[+ side].

Two conductors with a resistance of 2 Ohm and 6 Ohm are connected in series. Voltage drop on the first conductor

equal to 5V. Find the voltage drop across the second conductor. \u003d;

6Ω 5V \u003d 15V.

How will the modulus and direction of the interaction forces of two small metal balls change

diameter, having charges -20NKl and + 10Nkl, if the balls are brought into contact, and then moved apart to the previous

distance? The module will decrease, the directions will be reversed.

In an inhomogeneous electric field, an electric dipole unfolds its dipole moment ... along

the direction of the field lines and is drawn into the region of the stronger field.

The magnitude of the strength and potential of the field of a point charge depending on the distance from the charge to the point

observations behave like this: ~

With an increase in the electric field strength in a certain region by a factor of three, the volume energy density

electric field ... increases 9 times.

Two conductors with the same cross-section and different conductivities 1

and 2 are connected

consistently. What is the ratio of the electric field strengths 1 in both conductors? ...

6. In the field between the plates of a flat capacitor, a force of 50 μN acts on a charge of 0.2 μC. To what voltage is the capacitor charged if the distance between the plates is 0.03 m? \u003d; \u003d; \u003d \u003d... \u003d. IN.

1. An infinite uniformly charged hollow cylinder is given. How will the value of the electric field strength inside the cylinder change in the direction from the axis to its boundary? \u003d.

2. Compare the fluxes Ф of the field strength vector of the same point charges q for the four closed surfaces shown in the figure. F \u003d F \u003d F \u003d F.

3. How will the modulus and direction of the interaction forces of two small metal balls of the same diameter and charges change? -20nC and + 10nC, if the balls are brought into contact and then moved apart at the same distance? The module will decrease, the directions will be reversed.

4. An infinite plane-parallel plate made of a homogeneous isotropic dielectric with permeability is placed in a uniform electric field of strength perpendicular to the plane of the plate. What is the strength of the electric field inside the plate? ...

5. The current density is proportional to the speed of directional movement of current carriers in the conductor. The proportionality factor is equal to… the product of the carrier concentration by the charge of the current carrier.

6. In the diagram shown in the figure, through resistance1 current flows1 \u003d 1. What current flows through resistance2,

if resistance 2 is three times the resistance 3? \u003d +; \u003d; \u003d; \u003d; \u003d; \u003d; \u003d; \u003d + \u003d \u003d; \u003d \u003d. ...

1. The electrostatic field is created by a point charge located at the origin. The charge q can be moved and points K to points M, N and L. In what case will the work of external forces against the field forces be maximum? KN.

2. Charged the flat air condenser. Then, without changing the charge, the distance between the plates was increased threefold and the entire space between the plates was filled with a dielectric (\u003d 3). How has the capacitor energy changed? Hasn't changed.

3. The energy of interaction of two equal point charges of the same sign located at a distance L from each other,

expressed by the formula….

4. How will the field strength change inside a flat capacitor connected to the source if the distance between the plates is halved? Will not change.

5. The figure shows two connection diagrams of four identical resistances. Determine the ratio of the AB leg resistance to the CD leg resistance. ...

6. The radius of a uniformly charged hollow sphere is 3cm. Find the ratio of potentials 1 at the points of the field located

at a distance of 1cm and 4cm from the center of the sphere. \u003d		; inside the sphere \u003d on the surface \u003d

1. Charges of equal magnitude are located in the plane of the square, as shown in the figure. How is the electric field vector directed at the center of the square? Way down.

2. If the algebraic sum of the charges enclosed inside a closed surface is equal to zero, then it is equal to zero ... the flow of the intensity vector through this surface.

3. The vector of intensity and the potential of the electric dipole field, depending on the distance from the dipole to the observation point, behave as follows: 2. ~; ~.

4. Two infinite parallel planes are charged uniformly with equal surface charge densities. Determine the correct variant of the dependence of the potential of the electrostatic field on the coordinate. 3.1.

5. The current density in a conductor is proportional to the strength of the electric field. The proportionality factor is called ... conductivity.

6. A uniform electrostatic field with an intensity of 0.1 kV / m does 10 mJ of work to move a positive charge along the lines of tension at a distance of 1 m. Determine the value of the positive

1. Can an electric field outside from a system of two opposite and uniformly charged infinite parallel planes be nonzero? Not.

2. The sphere, uniformly and positively charged in volume, is immersed in a liquid dielectric. How will the intensity of the electrostatic field outside the sphere change in the direction from the boundary to infinity? You need to know the dielectric constant of the dielectric.

3. The potential of the dipole field is zero (at zero potential at infinity)… at no point in space.

4. In an external electric field ... the polarization vector of polar and non-polar dielectrics is nonzero.

5. The work done by external forces when a positive charge moves along a section of the circuit is numerically equal to ... the product of the charge by electromotive force on this site.

6. The bird sat down on a wire carrying a current of 2kA. Wire resistance for each meter of length is 2.5 10−5 Ohm, the distance between the paws of the bird is 5 cm. What voltage is it under? \u003d \u003d. ...

- \u003d .− \u003d. IN.

1. Choose the correct statement. The equipotential surfaces of the electrostatic field are always perpendicular to the lines of intensity.

2. In the common center of two cubes with edges equal to1 and 2, there is a point charge + Q. Compare the fluxes of the field strength vector of this charge through the faces of the cubes. The streams are the same and not zero.

3. The potential difference between the two points is… ∫.

4. Indicate the number under which both physical quantities are vectors: electrical displacement (induction), dipole moment.

6. Five lamps with a resistance of 440 Ohm are connected in parallel and connected to a 220V network. Find the power

consumed by lamps. \u003d \u003d \u003d \u003d B;									Ohm; \u003d Ohm; \u003d \u003d \u003d. ; \u003d

Answers by Sergei Sergeevich. I cannot vouch for the correctness

A metal ball with a radius of 10 cm is charged to a potential of 1500 V. How much heat will be released when it is grounded?

C ball \u003d 4pi * E * R \u003d 4 * 3.14 * 8.85 * 0.1 * 10 ^ (- 12) \u003d 1.1121 * 10 ^ (- 11) Farad

Q \u003d C * (U ^ 2) / 2 \u003d 0.000012511 J.

The flat air capacitor was charged and not disconnected from the voltage source. Then, the entire space between its plates was filled with a dielectric with a dielectric constant e \u003d 4. How did the energy of the capacitor change?

Not disconnected from the power source \u003d\u003e U \u003d const. W cond \u003d C * (U ^ 2) / 2. C \u003d e * E * S / d. e1 \u003d 1; e2 \u003d 4; Increased 4 times.

The circulation of the tension vector is 0 for ...

The theorem on circulation in electrostatics: the circulation of the vector of the strength of the electrostatic field along any closed loop is equal to zero. ... for any electric field.

The dielectric constant e is greater than unity in the case of ...... For any dielectric.

With one resistance of the rheostat, the voltmeter shows 6 V, the ammeter 1 A. With a different resistance of the rheostat, the instrument readings: 4 V and 2 A. Determine the internal resistance of the current source.

In general: e * R + r \u003d I<=> e \u003d R * I + r * I<=> e \u003d U + I * r. From the conditions we obtain the system: (e \u003d U1 + I1 * r; e \u003d U2 + I2 r \u003d\u003e U1 + I1 * r \u003d U2 + I2 * r, r (I2-I1) \u003d U1 -U2, r \u003d (U1-U2) / (I2-I1), r \u003d 2 ohms.

Point K is at a distance of 4 m, and point M is at a distance of 2 m from a point charge of 200 nC. Find the potential difference between points K and M. uk - um \u003d k * q / rm - k * q / rk \u003d kq (rk-rm) / (rk * rm) \u003d -450 V.

The strength of the electric field is numerically equal to ...... the force acting on a unit point charge located at a given point of the field.

The radius of the charged metal ball is 10 cm. The radius of the ball was increased by 3 times while maintaining its charge. How many times has the field strength changed at a distance of 50 cm from the center of the ball? Will not change

In the middle between two point charges q \u003d 12nC and q2 \u003d -4nC there is a charge q. This charge from the side of charge q2 is acted upon by a force of 6 μN. Determine the force acting on the charge q from both charges q1 and q2. 12 μN

The electric dipole is initially located in a uniform electric field so that its dipole moment is perpendicular to the field lines. What happens next with the dipole? It turns around so that its dipole moment is directed across the field, then stops.

A flat capacitor with capacitance C is connected to a voltage source with EMF e. What work needs to be done to double the distance between the capacitor plates? A \u003d W1 - W2 \u003d (e ^ 2) * q / 2d - (e ^ 2) * q / 4d \u003d (e ^ 2) * q / 4d \u003d (e ^ 2) * C / 4.

The electric energy of a charged ball is 0.15 mJ, its charge is 10 μC. Determine to what potential the ball is charged.

W \u003d q * u / 2 \u003d\u003e u \u003d 2W / q \u003d 30 V.

Which line correctly indicates the directions of a) the vector of the electric field strength created by the dipole at point A and b) the vector of the dipole moment? p \u003d q * l; vector l: "+" -\u003e "-" The field strength of the dipole on the perpendicular, raised to the axis from its middle, is oppositely directed to the vector p.

The electrostatic field is created by a system of two metal balls with charges -4q and -q. Indicate the point at which the field potential can be zero. There is no such point.

At some point of an isotropic dielectric with permittivity e, the electrical displacement (induction) has a value of D. What is the polarization P at this point? D \u003d e * E + P \u003d\u003e P \u003d D / (e * E) // Not completely sure

Three resistors with resistance R1 \u003d 1 Ohm, R2 \u003d 2 Ohm, R3 \u003d 3 Ohm are connected in parallel in the circuit direct current... What is the ratio of the powers allocated to these resistors? Resistor power in DC circuit P \u003d I ^ 2 * R Serial connection \u003d\u003e I is the same 1: 2: 3

Uniform field strength E \u003d 80 kV / m. Determine the potential difference between points 2 and 1 if the distance between them is 5 cm, and the angle b \u003d 60 *? U12 \u003d E * l * cos (b) \u003d 2000 V

The electric field is created by a volume-charged ball with the same bulk density charge. At some point of measurement, located inside the ball, the field strength is determined. How will this tension change when the distance from the center of the ball to the observation point decreases 2 times? Inside the ball E \u003d p * r / (3 * e0 * e1). Will decrease by 2 times

The charge of the sphere is 10 μC, its electric energy is 0.15 mJ. Determine to what potential the ball is charged. W \u003d q * u / 2 \u003d\u003e u \u003d 2W / q. 30 in

Choose the correct statement for the change in the interaction force of two point charges when they are transferred from a vacuum to a homogeneous isotropic dielectric (e \u003d 2). According to Coulomb's law, the force of interaction of two point charges is directly proportional to the product of charges, inversely proportional to the square of the distance between them and the dielectric constant of the medium \u003d\u003e In a dielectric, the force will decrease by 2 times.

The current source with internal resistance r is closed to the load resistance R. Which or which of the graphs qualitatively correctly reflect the dependence of n (efficiency of the current source) on R? n \u003d U / E \u003d IR / (I (R + r)) \u003d R / (R + r); R -\u003e inf; n -\u003e 1; But at the same time, the current in the circuit is small and the power is small.

Two bulbs with a resistance of 6 ohms and 1.5 ohms are alternately connected to some current source and consume the same power. Determine the internal resistance of the current source. P1 \u003d P2; (1) P \u003d I ^ 2 * R \u003d e ^ 2 * R / ((R + r) ^ 2)

(2) (2) in (1) + cancel e ^ 2: R1 / (R1 + r) ^ 2 \u003d R2 / (R2 + r) ^ 2 express r: r \u003d sqrt (R1 * R2); r \u003d 3 Ohm

What resistance should be connected in parallel to the 21 Ohm resistance so that the resistance of the section is

6.3 Ohm? 1 / R \u003d 1 / R1 + 1 / R2; R2 \u003d R1 * R / (R1-R); R2 \u003d 9 Ohm

The electric field is created by a uniformly charged hollow sphere. At some point of measurement, located outside the sphere, the field strength is determined. How will this tension change when the distance from the center of the sphere to the observation point is doubled? Will decrease by 4 times

The equipotential surfaces of the field of a point positive charge have the form of ... concentric spheres

An isotropic dielectric (permittivity e) in the form of a straight parallelepiped is in a uniform electric field, and the field lines are perpendicular to one of the faces. Determine how the value of the field strength E and the electric induction D in the dielectric will change in comparison with vacuum. E \u003d E0 - sigma / e0; E0 - external field, sigma - surface charge density. D \u003d e * e0 * E There is no final answer.

The density of the electric current in a homogeneous conductor with an increase in the electric field strength by 2 times ... j \u003d sigma * E, where sigma is the specific conductivity of the medium. Will double.

On the resistance R, when an electric current I flows through it during a time t, an amount of heat Q is released, for which the following expression is true: Q \u003d I ^ 2 * R * t

A battery of two series-connected capacitors with a capacity of 200 nF is supplied with a voltage of 300 V. Find the energy stored in the battery. C \u003d C1 * C2 / (C1 + C2) \u003d 100nF. W \u003d C * U ^ 2/2 \u003d 50 * 300 ^ 2 * 10 ^ (- 9) \u003d 4.5 * 10 ^ (- 3) J

If the potential of the electric field at infinity is zero, then at any point of the field the potential is numerically equal to ... the work of the field in moving a unit positive charge from a given point of the electric field to infinity

Two similarly named point charges approach each other, sliding along an arc of a circle. How do the field strength and potential at the center of this circle change? The magnitude of the tension increases, the potential does not change (This is due to the fact that the tension has a vector superposition, and the potential is scalar).

The flat air capacitor was charged and not disconnected from the voltage source. Then the distance between the plates was doubled. How did the energy density of the capacitor field change? Unchanged w \u003d W / Sd \u003d 1/2 * CU ^ 2 / (Sd) Considering that C \u003d Eps * Eps * S / d (Eps \u003d Epsilon) and U \u003d Ed, w \u003d Eps * Eps * E ^ 2/2 This function is independent of the distance between the plates.

According to the Joule-Lenz law, the power released at the resistance R when the current I flows through it and the voltage U drops across it is equal to: U ^ 2 / R

The normal n to the flat area dS makes an angle alpha with the electric field density vector j. Select the correct expression for the current through the pad. j * dS * sin (alpha) (j normal to dS)

Three identical capacitors are connected one time in series, the other in parallel. What is the C2 / C1 ratio? 1/9 For the first case (sequentially), 1 / C1 \u003d 1 / c + 1 / c + 1 / c \u003d 3 / c \u003d\u003e c1 \u003d c / 3 For the second case (parallel), C2 \u003d C + C + C \u003d 3C But you can divide it yourself.

Compare the fluxes Ф of the field strength vector of the same point charges q for four closed surfaces

3 Ф1 \u003d Ф4\u003e Ф2, Ф3 \u003d 0

IN closed circuit positive free charges - 1 move in the direction of increasing potential in the area of \u200b\u200baction of external forces, and in the area of \u200b\u200baction of electrostatic forces - in the direction of decrease

The vector of the intensity of the electrostatic field in relation to the lines of intensity is directed - 5 tangentially in the direction of decreasing potential.

Dielectric ball in an inhomogeneous electric field - 3 will move to the left

How will the field strength change inside a flat capacitor, charged and disconnected from the source, if the area of \u200b\u200bthe plates is doubled - 4 it will decrease by 2 times

What happens to the readings of the voltmeter and the brightness of the bulb when the rheostat is shifted to the right - 3 readings increase, the brightness decreases

Two capacitors C1 and C2 are connected in series. The total capacitance C "is 3 μF. Determine the value

electrical capacity C1, if C2 \u003d 4 μF solution: 1 / С "\u003d 1 / С1 + 1 / С2 С" \u003d С1 * С2 / (С1 + С2) С1 \u003d 12 μF

1. Lines of force homogeneous magnetic field are perpendicular to the plane of the contour (from us to the drawing), the current in which is directed clockwise. The Ampere force acting from a uniform magnetic field on the contour ... tries to stretch the contour in its plane.

2. Choose the correct expression for the magnetization vector.∆ ∆ .

3. - the magnetic susceptibility of diamagnets, - the magnetic moment of their atoms. Which statement is true?< , | | , = .

4. The rate of change of the magnetic flux penetrating the circuit is numerically equal to ... the EMF induced in the circuit.

5. Indicate the line in which the expression for the Lorentz force and the rule that must be followed when determining the direction of the force vector for a positive charge are correctly presented. , left hand rule.

6. What is the period of the oscillation described by the equation \u003d 2 sin (2 + ⁄6)? From the condition \u003d. \u003d √, \u003d \u003d

√, √ \u003d \u003d, \u003d \u003d с.

1. The magnitude of the magnetic induction vector of the field of an infinite forward current depends on the distance between the observation point and the conductor with current as follows ... ~ ⁄.

2. The flux of the vector of magnetic induction (magnetic flux) through the closed surface is equal to ... zero.

3. Which formula correctly describes the energy of the magnetic field created by a circuit with current and inductance (

Is the total magnetic flux penetrating the circuit)? \u003d.

4. The nature of the EMF induction when the conductor moves in a constant magnetic field is due to the force of ... Lorentz.

5.1-year NRU ITMO wrote the following Maxwell equations in

6. A straight conductor with a length of 40 cm and a current of 2.5A is placed in a uniform magnetic conductor with an induction of 0.07T. Determine the force acting on the conductor from the side of the field if the direction of current movement makes an angle of 30 ° with the lines of force.

1. From the proposed list, select the vector quantities: magnetic induction, current strength, magnetic moment, flux Ф of the magnetic induction vector. ,.

2. In one plane, there are two mutually perpendicular conductors with equal currents... Specify the points at which the magnetic induction is zero. 1 and 3.

3. How will the magnitude of the magnetic field strength inside the solenoid change if a magnet with permeability \u003d 9 is removed from it? It will decrease by 9 times.

4. Under what number are the expressions that determine: a) the coefficient of mutual induction12 and b) the energy of the magnetic field created by two circuits with currents 1 and 2 (2 is the total magnetic flux penetrating the second

circuit due to the primary circuit current,

- inductance, respectively, of the first and second circuits)? \u003d

5. A beam of positively charged particles flies into a uniform electric field perpendicular to the vector. How should the magnetic induction vector be directed to compensate for the deviation

beam created electric field? The vectors shown in the figure lie in the plane of the drawing. Per

6. A kettlebell suspended from a spring vibrates vertically with an amplitude of 4 cm. Determine the total vibration energy of the weight if the spring stiffness is 1 kN / m.full \u003d kin + pot \u003d +. At the moment of maximum displacement \u003d.

Therefore, at this moment

= = . .

1. What physical quantity has in SI units the dimension equal to Cl B?

2. The figure shows sections

two parallel

straight long

conductors with oppositely directed currents 1 and 2,

where 1 \u003d 22.

The magnetic induction of the resulting magnetic field is zero at some

interval point… d.

3. The coefficient of mutual induction of two circuits with a current in a vacuum depends only on ... the size, shape of the circuits, the distance between them and their mutual orientation.

4. Which line correctly reflects the properties of diamagnets and their constituent molecules (- magnetic susceptibility)? The value is small and negative, the intrinsic magnetic moment of the molecules is zero.

5. Under what number is the solenoid inductance correctly represented (- relative magnetic permeability,0

Is the magnetic constant, is the number of turns per unit length of the solenoid, is its length, is the cross-sectional area, the length of the solenoid is many times greater than its diameter)? \u003d.

6. A material point with a mass of 20g oscillates according to the law \u003d 0.1 cos (4 +4), m. Determine the total energy of this point. Full \u003d kin + pot \u003d +. At the moment of passing the equilibrium state, the displacement is equal to zero \u003d, and

speed is maximum. Therefore, at this moment

\u003d ′ \u003d -. (+). From here

the maximum value of the speed modulo will be equal to. ; Consequently,

1. Two infinitely long parallel conductors with currents approach each other, moving along an arc of a circle. How does the modulus of magnetic field induction change in the center of this circle for the case of parallel and for the case of antiparallel conductors? The plane on which the circle is located is perpendicular to the current carrying conductors. For parallel it increases, for antiparallel it decreases.

2. The lines of magnetic induction of the field of an infinite direct current have the form of ... concentric circles.

3. Indicate the expression that determines the dependence of the magnetic susceptibility on temperature for paramagnets (is the Curie constant). \u003d /.

4. How does a uniform magnetic field with induction act on a rectangular frame with current? Turns the frame side to us.

5. The oscillating circuit consists of an inductor and two identical capacitors connected in parallel. How will the oscillation period of the circuit change if the capacitors are connected in series? Will decrease by 2 times.

6. One mathematical pendulum has a period of 3s, the other 4s. What is the period of oscillation of a mathematical pendulum, the length

1. The unit of measurement of magnetic induction is ... Tesla.

3. The flux of the magnetic induction vector through a closed surface ... is always zero.

4. The magnetic flux through the coil changes over time according to the graph. In what interval does the induction EMF have the minimum in absolute value, but not equal to zero? -.

5. Exam testing in physics student 1st year SPbSUITMO presented the following Maxwell equations in integral form. Did he make a mistake in them, and if so, in what equation?

6. A weight of 250 g, suspended from a spring, vibrates vertically with a period of 1 s. Determine the stiffness of the spring. \u003d

1. Choose the correct expression for the magnetic field vector. -.

2. The induction vector of a uniform magnetic field is directed from left to right. A conductor with a direct current is located perpendicular to the plane of the drawing (the current flows from us). Select the point at which the total induction can be zero. four.

3. How will the energy stored in the magnetic field of the solenoid change if the solenoid current is halved and at the same time the inductance of the solenoid is doubled? Will decrease by half.

4. In an external magnetic field0 placed a glass of water, the molecules of which do not have their own magnetic moment. What will be the magnitude of the magnetic field in water and how will the magnetization vector of water be directed? will become less

by a fraction of a percent, the vector will be directed along the vector.

5. A beam of positively charged particles passes through uniform electric and magnetic fields directed perpendicular to the beam movement. How should the magnetic induction vector be directed to compensate for the deflection of the beam created by the electric field? In the positive direction of the axis.

6. A point charge flies into a uniform magnetic field with an induction of 2T at a speed of 15m / s. The vector of velocity and magnetic induction makes up an angle of 30 °. The magnitude of the Lorentz force acting on the particle from the side of this field is 0.5 mN.

1. Unit eMF measurements self-induction is ... Volt.

2. Two straight conductors 1 and 2 with currents, respectively,1 and 2 are parallel. How is the magnetic field created by the first conductor directed at the place where the second conductor is located, and how is the Ampere force acting on the second conductor directed? directed beyond the drawing, pointing up.

3. How will the energy stored in the magnetic field of the solenoid change if the solenoid current doubles and at the same time the solenoid inductance decreases fourfold? Will not change.

4. A positively charged particle moves from an infinite current carrying conductor. The force acting on the particle will ... decrease, deflecting the particle upward.

Which of the formulas is the equation of damped oscillations (is the damping coefficient, 0

- own

vibration frequency)? ′ ′ + ′ + \u003d.

A charged particle moves in a uniform magnetic field along a circle of radius 1. After increasing the field induction

and the particle velocity is 2 times the radius of the circle became. Find an attitude

1. Homogeneous is the magnetic field ... inside an infinite solenoid.

2. Indicate the direction of the force acting on the conductor with current density. five.

3. In an external magnetic field0 placed a piece of paramagnetic aluminum. What will be the magnitude of the magnetic field inside aluminum and how will the magnetization vector of aluminum be directed? becomes larger by a fraction of a percent, the vector will be directed along.

4. What rule does the direction of Foucault's currents obey? Lenz's rule.

5. Which of the formulas is the equation of forced vibrations (is the damping coefficient,0 is the natural frequency of oscillations, is the value proportional to the amplitude of the driving force, is the frequency of the driving force)? ′ ′ + ′ + \u003d.

6. Flat conductive loop 100cm2 is located in a magnetic field perpendicular to the magnetic field lines. The magnetic induction changes according to the law \u003d (1 - 32) 10−3 T. Determine the EMF of the induction that occurs at the time \u003d 2s. \u003d −Ф \u003d - \u003d −− - (-) \u003d - \u003d, mV.

1. A circuit with a current is in a magnetic field, is its magnetic moment,max - maximum torque, min - minimum torque. The magnitude of the magnetic induction vector is equal to… max ⁄.

2. From the values \u200b\u200blisted below, select the one that does not affect the inductance of the solenoid in a non-ferromagnetic environment. Depends on the number of turns per unit length, the cross-sectional area of \u200b\u200bthe solenoid, the length of the solenoid, and the magnetic permeability of the medium.

3. Which line contains three correct expressions for the energy density of the magnetic field in an isotropic magnet

(Is the relative permeability, 0 is the magnetic constant, is the magnitude of the magnetic induction vector, is the magnitude of the magnetic field strength vector)? \u003d, \u003d, \u003d.

4. The magnetic flux penetrating the coil changes over time according to the graph. In what interval is the EMF of induction equal to zero? -.

5. Which statement about the properties of conduction currents and coupling currents is correct? Both currents create a magnetic field.

6. An electron moves in a circle in a uniform magnetic field of 10 kA / m. Calculate the period of rotation of an electron. Consider the specific charge of an electron to be 1.8 * 1011 C / kg, magnetic constant 0 \u003d 4 10−7 H / m. L \u003d q; l \u003d

\u003d; \u003d; q \u003d; \u003d; \u003d; \u003d; \u003d										\u003d. - p.

1. Currents in two parallel conductors are equal in size and directed in opposite directions. Determine the direction of the resulting vector of magnetic induction at point A. Up.

2. Compare the circulation of the magnetic field strength vector of an infinite forward current, perpendicular to the plane of the figure, along a closed loop in four cases. \u003d \u003d; \u003d.

3. Choose the correct ratio for the directions of the vectors of strength, magnetic induction and magnetization in a homogeneous isotropic diamagnet. and directed the same way - in the opposite direction.

4. A closed conductor is in a uniform magnetic field directed beyond the drawing. The induction decreases over time. Determine the direction induction current in the explorer. Clockwise.

5. Two protons with different energies fly into a uniform magnetic field. What trajectory corresponds to the highest energy proton? Trajectory 2.

6. A capacitor with a capacity of 2 μF is included in the oscillatory circuit. What is the total energy stored in

		if the capacitor charge (in C) changes according to the law \u003d 0.02 sin (12345)? \u003d

1. Select the line in which the physical quantities have the dimension A / m (- tension

magnetic field, - magnetic permeability, - magnetization of the magnet, - current density, - magnetic moment). ,.

2. Compare the moduli of the magnetic field in the center of the loop with the current for the three conductor configurations. \u003e\u003e.

4. Whether tungsten (\u003d 1.000176), platinum (\u003d 1.000360) and bismuth (\u003d 0.999524) are paramagnets. Only tungsten and platinum are relevant.

5. The following system of Maxwell equations

valid ... only in the absence of conduction currents.

6. A 500nF capacitor is connected in parallel with a 1mH inductor. Determine the oscillation period of the oscillator. \u003d √ \u003d √- - \u003d. - with \u003d. μs.

1. The circulation of the magnetic field strength vector is zero ... then, if the circuit does not cover currents.

2. In Boris Leonidovich Pasternak's poem "Explanation" there is such a stanza. What are the locations of the two forward currents talking about? A variant where currents are co-directed and parallel to each other.

3. The properties of the magnetic field strength of an infinite solenoid (is the solenoid current). Inside the solenoid, the field is uniform and \u003d (is the number of turns per unit length of the solenoid). Outside the solenoid, the field is zero.

4. A proton and a particle (\u003d 2; \u003d 4) are accelerated to the same energy and fly into the magnetic field at different angles of 30 ° and 60 °, respectively, to the direction of the magnetic induction vector. How the periods of rotation of a proton are related

(1) and particles (2)? \u003d.

5. During the physical examination, a first-year student of NRU ITMO presented the following Maxwell equations in integral form. Did he make a mistake in them, and, if so, in what equation. Look at the application. If everything coincided with the equations of the complete system, then the answer is “no error”.

6. The damped oscillation equation has the form′ ′ + 0.5 ′ + 900 \u003d 0.1 cos 150. The damping coefficient is much less than the natural frequency of oscillations. How much should the frequency of the driving force be reduced for resonance to occur? Of

	the equation implies that \u003d;	= ; = . ;

1. How is a circuit with a current located in its free orientation in a uniform magnetic field? The normal to the contour is parallel to the magnetic induction vector.

2. The magnitude of the magnetic induction vector in the center of a circular conductor with radius and current strength is equal to….

3. The circulation of the magnetic field strength vector when walking along the contour piercing the conductors with the current is equal to ... the algebraic sum of the currents penetrating the contour.

4. - the magnetic susceptibility of paramagnets, - the magnetic moment of their atoms. Which statement is true? \u003e, | | , ≠.

5. Two electrons with different energies fly into a uniform magnetic field. What trajectory of motion corresponds to the electron with the lowest energy? Trajectory 5.

6. Wobble material point with a mass of 0.1 g occurs according to the equation \u003d cos, where \u003d 5 cm, \u003d 20s-1. Define

maximum value of restoring forces. \u003d \u003d -; max \u003d \u003d. ... \u003d. N.

1. The unit of measure for the mutual induction coefficient is ... Henry.

2. The magnitude of the magnetic induction vector of the field of an infinite forward current depends on the distance between the observation point and the conductor with current as follows ....

3. The elementary work of the Ampere force when moving a circuit with a current in a magnetic field is equal to the product of the current in the circuit ... by the change in the magnetic flux penetrating the circuit. Fora \u003d ∫.

4. The magnetic flux through the coil changes over time according to the graph. In what time interval does the induction EMF have the minimum in absolute value, but not equal to zero? -. For the EMF of induction depends on the rate of change of the flux.

5. The voltage across the capacitor in the oscillatory circuit is described by the expression \u003d0 (2). IN

what moment of time the magnetic field energy in the coil is maximum (- period)? \u003d.

6. A point charge flies into a uniform magnetic field with an induction of 2T at a speed of 15 m / s. The vectors of velocity and magnetic induction make up an angle of 30 °. Find the value of the charge if the Lorentz force acting on the particle from the side of the field is

1. Indicate the line in which the Bio-Savart-Laplace law and the rule that must be followed when determining the direction of the magnetic induction of a current element are correctly represented. \u003d [×], right screw rule.

2. Select the correct expression for the magnetization vector. -.

3. The conductor moves in a uniform magnetic field. The potential of which of the two points of the conductor (s) is higher? The potentials are the same.

4. Exam testing in physics student 1st year NRU ITMO presented the following Maxwell equations in integral form. Did he make a mistake in them, and if so, in what equation? \u003d ∫.

5. The total energy of a mechanical oscillator, oscillating according to the law \u003d sin… is proportional.

6. A 500pF capacitor is connected in parallel with a 1mH inductor Determine the oscillation period

oscillator. \u003d √ \u003d √ - - \u003d .− s.

1. Properties of magnetic ley lines (lines of magnetic induction). The lines are located so that the tangents to these lines would coincide in direction with the magnetic induction vector.

2. An infinitely long straight conductor with current runs along the axis of the circular circuit with current. How does the magnetic field of a conductor act on a circular circuit? Doesn't work in any way.

3. The magnetic susceptibility is less than zero in the case of ... only diamagnets.

4. A closed conductor is in a uniform magnetic field. The induction increases over time. Determine the direction of the induction current in the conductor. If the current is directed away from the observer, then clockwise. If on - counterclockwise.

5. What kind of energy does an ideal oscillatory circuit contain in half the period after the start of the capacitor discharge? Electric only.

6. Flat contour 250cm2 is in a uniform magnetic field with an induction of 0.2T. Find the magnetic flux

if its plane makes an angle of 30 degrees with the lines of induction. Ф \u003d; Ф \u003d \u003d, \u003d, Wb.

1. The unit of measure for the mutual induction coefficient is ... Henry.

2. In an isotropic magnet with permeability, the magnetic induction is equal to. Choose the correct expression for the magnetic field strength. ...

3. Under what number are the expressions related to the inductance of the circuit correctly represented? (- full magnetic

the flux penetrating the circuit, is the current in the circuit, is the induction EMF that occurs in the circuit, is the magnitude of the magnetic induction)? \u003d; \u003d -.

4. Which light on the diagram will light up the latest after the key is closed? 3. Inductance will interfere with the flow of current.

5. How the frequency will change electromagnetic waves, if a ferrimagnetic core is introduced into the inductor? Will increase.

6. An electron moves in a circle in a uniform magnetic field of 10 kA / m. Calculate the rotation period

magnetic constant

4 10-7 H / m.

c; l \u003d \u003d; \u003d; q \u003d; \u003d; \u003d; \u003d; \u003d

- p.

For reference on tasks for Maxwell's equations: Complete system, taking into account everything that is possible:

IN the absence of charged bodies changes:

IN the absence of conduction currents changes:

Guys, I will not hand over these tasks, the only 3 will come out! Help) 1. What is the resistance of 1m of a constantan wire with a diameter of 0.8 mm? 2.When

winding a coil of copper wire, its mass increased by 17.8 r, and the resistance turned out to be 34 ohms. Estimate from these data the length and cross-sectional area of \u200b\u200bthe wire?

3.An ammeter and a resistor with a resistance of 2 Ohm were connected in series to a current source with an internal resistance of 1 Ohm. The ammeter showed 1 A. What will the ammeter show if you use a resistor with a resistance of 3 Ohm?

4.In the circuit, the voltmeter shows 3V, and the ammeter is 0.5 A. At a current of 1A, the voltmeter shows 2.5 V. What are the EMF and internal resistance of the source?

5.A charge of 3C in an electrostatic field is affected by a force of 6 N. What is the field strength?

a.18 n / a b 0.5 n / a c. 2 n / a c g 24 n / a c. among the answers there is no correct

6. How will the strength of the electric field of a point charge, transferred from a vacuum into a medium with a dielectric constant equal to 81, change?

a. will increase by 9 times b. decrease by 9 times c. will increase in 81 d. decrease by 81 times e. will not change

10.When moving the electric charge between the points with a potential difference of 8 V, the forces acting on the charge from the side of the electric field did a work of 4 J. What is the value of the charge?

a.4kl b. 32 cl. 0.5 cl. 2 cl. no correct

11.Charge 2kl moves from a point with a potential of 10 V to a point with a potential of 15 V. What work does the electric field do in this case?

a. 10 j b. -10 j c. 0.4 j g. 2.5 j d. no correct

12.when moving a charge of 3 cells from 1 point to another, the electric field does work 6 J. What is the potential difference between these points?

a.18 c b 2 c c 0.5 v d 9 c d. no correct

13. How will the electrical capacity of a capacitor change when a dielectric with a dielectric constant of 2 is removed from it?

1) How will the force of the Coulomb interaction of two small charged balls change with an increase in the charge of each of them 2 times, if the distance between

balls remains unchanged?

A. Will increase 2 times. B. Will not change. B. Will increase 4 times. D. Will decrease by 2 times.

D. Will decrease by 4 times.

2) What carriers of an electric charge is created electricity in metals?

A. Electrons and positive ions. B. Positive and negative ions. B. Positive, negative ions and electrons D. Only electrons. D. Among answers A - D there is no correct one.

3) The heat engine per cycle receives from the heater the amount of heat 100 J and gives to the refrigerator 60 J. What is the efficiency of the machine?

A. 67%. B. 60%. B. 40%. G. 25%. D. Among answers A - D there is no correct one.

4) How will the pressure of an ideal gas change with an increase in the concentration of its molecules by 3 times, if the mean square velocity of the molecules remains unchanged?

A. Will increase 9 times. B. Will increase 3 times. B. Will remain unchanged. D. Will decrease by 3 times. D. Decrease 9 times.

5) How will the average kinetic energy of the thermal motion of ideal gas molecules change with an increase in the absolute gas temperature by 3 times?

A. Will increase 3 times. B. Will increase by 2 times. B. Will increase by 4.5 times. D. Will increase 9 times.
6) Estimate the approximate mass of air volume 1 m3 at normal atmospheric pressure and a temperature of 300 K. From the values \u200b\u200bbelow, select the one that is closest to your result.

A. 1 G. B. 10 G. C. 100 G. 1 kg. D. 10 kg.

Physical dictation

“Electrification of tel. Electric charge conservation law "

1. What is the name of the section of physics that studies charged bodies?

2. What kind of interaction exists between charged bodies, particles?

3. What physical quantity determines the electromagnetic interaction?

4. Does the amount of charge depend on the choice of the frame of reference?

5. Can we say that the charge of a system is the sum of the charges of the bodies included in this system?

6. What is the name of the process leading to the appearance of electric charges on bodies?

7. If the body is electrically neutral, does this mean that it does not contain electric charges?

8. Is it true that in a closed system the algebraic sum of the charges of all bodies in the system remains constant?

9. If in a closed system the number of charged particles has decreased, does this mean that the charge of the entire system has also decreased?

_____________________________________________________________________________

Physical dictation

“The law of conservation of electric charge. Coulomb's Law ".

1. Can you create an electric charge?

2. Do we create an electric charge during electrification?

3. Can a charge exist independently of particles?

4. Body, total positive charge particles of which is equal to the total negative charge particles is ...

5. Force of interaction of infected particles with increasing charge of any of these particles?

6. When charges are placed in a medium, the force of interaction between them ...

7. With an increase in the distance between charges by 3 times, the interaction force ...

8. The quantity characterizing the electrical properties of the medium is called ...

9. In what units is the electric charge measured?

Physical dictation “Electrification of bodies.

Electric charge conservation law. Coulomb's Law ".

Capacitors
1. The ability of a conductor to accumulate a charge is called ...
2. In what units is the electrical capacity measured?
3. What is the name of the system of two conductors separated by a dielectric layer?
4. What is meant by the charge of a capacitor?
5. Where is the capacitor's electric field concentrated?
6. How will the capacitance of a capacitor change if a dielectric is introduced between the plates?
7. Does the capacitance of the capacitor depend on the geometric dimensions?

Answers
1.… electrical capacity
2. In farads
3. Capacitor
4. Charge module of one of the plates
5. Inside, between the plates
6. Increase
7. Yes